#include <iostream>
#include <vector>

using namespace std;

bool cmp(vector<int>& A,vector<int>& B)
{
	if(A.size() != B.size()) return A.size()-B.size();
	for(int i = A.size()-1;i>=0;i--)
		if(A[i]!=B[i])
			return A[i]>B[i];
	return true;
}


vector<int> sub(vector<int>& A,vector<int> &B)
{
	vector<int> c;
	int t = 0;
	for(int i = 0;i<A.size();i++)
	{
		t = A[i] - t;
		if(i<B.size())	t = t - B[i];
		c.push_back((t+10)%10);
		if(t<0) t = 1;
		else t = 0;
	}
	while(c.size()>1 && c.back() == 0) c.pop_back();
	return c;
}

int main()
{
	string a,b;
	cin >> a >> b;
	vector<int> A,B;
	for(int i = a.size()-1;i>=0;i -- ) A.push_back(a[i]-'0');
	for(int i = b.size()-1;i>=0;i -- ) B.push_back(b[i]-'0');
	
	if(cmp(A,B))
	{
		auto c = sub(A,B);
		for(int i = c.size()-1;i>=0;i--) printf("%d",c[i]);
	}
	else
	{
		auto c = sub(B,A);
		printf("-");
		for(int i = c.size()-1;i>=0;i--) printf("%d",c[i]);
	}
	
	return 0;
}
